Endoprosthesis delivery system  with improved retraction

ABSTRACT

The present disclosure includes an endoprosthesis delivery system comprising an elongate member, such as a catheter, an endoprosthesis, and an end cap having one or more protrusions extending therefrom. The protrusions may assist in retraction of end cap into an outer sheath, such as an introducer sheath. In some examples, the protrusion includes fins. In some embodiments, the endoprosthesis delivery system further includes a covering member disposed about the endoprosthesis. The protrusions may support the covering member, which may extend beyond the distal end of the endoprosthesis and onto the end cap. In some embodiments, the end cap comprises a tapered profile, which may assist in retraction of the catheter tip and end cap into an outer sheath.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/826,040, filed Aug. 13, 2015, now U.S. Pat. No. 10,195,064, issuedFeb. 5, 2019, which claims the benefit of U.S. Provisional Application62/038,000, filed Aug. 15, 2014, both of which are incorporated hereinby reference in their entireties for all purposes.

FIELD

The present disclosure generally relates to endoprostheses for treatingdiseases of the vasculature and similar anatomies, and moreparticularly, to endoprosthesis delivery systems with at least one endcap proximal to a distal tip of the endoprosthesis delivery system.

BACKGROUND

Many endoprosthesis, such as, for example, stent-grafts, are constructedto reinforce, replace, bridge, or otherwise treat a part of a bloodvessel. An endoprosthesis may guide blood flow through a lumen definedby a generally tubular interior of such a vessel. Other tubularendoprostheses are designed for use in other body regions, for example,the esophagus, ureters, gastrointestinal tract and various ducts. Inmany cases, endoprostheses are constrained within a covering member orsheath and delivered to the body region requiring treatment on the endof an elongate member. When the covering member is removed, as duringdeployment, the devices are expanded under force or self-expand toassume a larger diameter. After delivery and deployment of theendoprosthesis, the elongate member used to delivery and deploy theendoprosthesis is retracted into a tubular outer shaft and removed fromthe body. In some instances, it may be difficult to properly align theelongate member and endoprosthesis with the outer shaft, causingdifficulties in retraction. Thus, improved endoprosthesis deliverysystems are desirable.

SUMMARY

Endoprosthesis delivery systems in accordance with the presentdisclosure can comprise an elongate member, an endoprosthesis comprisinga distal end, an end cap having a cylindrical body, wherein the end capis coupled to the elongate member adjacent to the distal end of theendoprosthesis, and a covering member surrounding a portion of theendoprosthesis, wherein a distal end of the covering member extendsbeyond the distal end of the endoprosthesis, and wherein a proximal endof the end cap comprises a tapered profile.

Endoprosthesis delivery systems in accordance with the presentdisclosure can further comprise a tip adjacent a distal end of the endcap. The tip can have a diameter larger than a diameter of the end cap.The tip and end cap can be integrated. The end cap can comprise a regionof reduced diameter located between the proximal end and the distal endof the end cap. The distal end of the covering member can be positionedin the region of reduced diameter. The proximal end of the tip can bespaced apart from the distal end of the end cap. The distal end of thecovering member can be positioned between the proximal end of the tipand the distal end of the end cap. The proximal end of the end cap cancomprise a fin. The fin can be angled relative to a longitudinal axis ofthe end cap, and the fin can fold upon retraction of the end cap intothe catheter The covering member can comprise a plurality of knitfibers, which can be woven about an exterior surface of theendoprosthesis and constrain the endoprosthesis in a constrainedconfiguration. The delivery system can further comprise a pull linecoupled to the covering member. The endoprosthesis can be a stent orstent-graft or similar device. The elongate member can be a guide wire.The delivery system can further comprise a catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present disclosure will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, wherein:

FIG. 1 illustrates a perspective view of an endoprosthesis deliverysystem in accordance with the present disclosure;

FIG. 2 illustrates a perspective view of a combined tip and end cap ofan endoprosthesis delivery system in accordance with the presentdisclosure;

FIGS. 3A, 3B, and 3C illustrate partial cross sectional views ofcombined tips and end caps of endoprosthesis delivery systems inaccordance with the present disclosure;

FIGS. 4A, 4B, and 4C illustrate side views of combined tips and end capsof endoprosthesis delivery systems in accordance with the presentdisclosure;

FIG. 5 illustrates a magnified perspective view of a portion of an endcap of an endoprosthesis delivery system in accordance with the presentdisclosure; and

FIG. 6 illustrates a magnified perspective view of a portion of an endcap of another endoprosthesis delivery system in accordance with thepresent disclosure.

DETAILED DESCRIPTION

Persons skilled in the art will readily appreciate that various aspectsof the present disclosure can be realized by any number of methods andapparatuses configured to perform the intended functions. Stateddifferently, other methods and apparatuses can be incorporated herein toperform the intended functions. It should also be noted that theaccompanying drawing figures referred to herein are not all drawn toscale, but may be exaggerated to illustrate various aspects of thepresent disclosure, and in that regard, the drawing figures should notbe construed as limiting. Finally, although the present disclosure maybe described in connection with various principles and beliefs, thepresent disclosure should not be bound by theory.

The terms “endoprosthetic device,” “endoprosthesis,” “vascular device,”and the like can refer, throughout the specification and in the claims,to any medical device capable of being implanted and/or deployed withina body lumen. In various instances, an endoprosthesis can comprise astent, a stent-graft, graft, a filter, an occluder, a balloon, a lead,and energy transmission device, a deployable patch, an indwellingcatheter, and the like.

In addition, throughout this specification and claims, the deliverysystems described herein can, in general, include an endoprosthesisconstrained by a “covering member” or “sheath.” The covering member orsheath can, in various embodiments, comprise a sheet of material that isfitted about an endoprosthesis. The covering member or sheath can, invarious embodiments, comprise a plurality of knitted fibers locatedabout the endoprosthesis. These fibers can, for example, comprise awoven warp knit or knit-braid, as described in U.S. Pat. No. 6,315,792to Armstrong et al., issued Nov. 13, 2001, entitled “Remotely removablecovering and support,” which is incorporated herein, in its entirety, byreference. The covering member can be coupled to a pull line extendingdown the length of the catheter, which a clinician can pull tofacilitate uncovering the endoprosthesis.

For example, a covering member comprising a plurality of fibers can becoupled to a pull line, which a clinician can pull to unravel theplurality of fibers. Thus, the covering member can be characterized as“unzipped”, in that the pull line causes the covering member to open orunzip along a straight line. In addition, in various embodiments, acovering member can be unzipped, first, along a proximal vector and,second, along a distal vector. In various embodiments, a covering membercan be unzipped along a longitudinal vector running substantiallyparallel to the longitudinal axis of an elongate member.

As used throughout the specification and in the claims, the term“elongate member” can refer to a shaft-like structure such as acatheter, guidewire, or the like. In various embodiments, anendoprosthesis can be mounted or loaded on a catheter, also referred toherein as an inner shaft.

As used throughout the specification and in the claims, the term “outershaft” can refer to a tubular element comprising a lumen, into which theendoprosthesis in a constrained diameter may be inserted and deliveredinto the body of a patient. Outer shafts can comprise, for example, anintroducer sheath, among other suitable constructs.

Further, the term “distal” refers to a relative location that is fartherfrom a location in the body at which the medical device was introduced.Similarly, the term “distally” refers to a direction away from alocation in the body at which the medical device was introduced.

The term “proximal” refers to a relative location that is closer to thelocation in the body at which the medical device was introduced.Similarly, the term “proximally” refers to a direction towards alocation in the body at which the medical device was introduced.

With continuing regard to the terms proximal and distal, this disclosureshould not be narrowly construed with respect to these terms. Rather,the devices and methods described herein may be altered and/or adjustedrelative to the anatomy of a patient.

As used herein, the term “constrain” may mean (i) to limit expansion,occurring either through self-expansion or expansion assisted by adevice, of the diameter of an expandable implant, or (ii) to cover orsurround an expandable implant (e.g., for storage or biocompatibilityreasons and/or to provide protection to the expandable implant and/orthe vasculature).

As used herein, the term “integral” refers to elements or componentswhich are connected and/or coupled to each other such that they form asingle physical object or structure.

In various embodiments, an endoprosthesis delivery system can comprisean elongate member, such as a catheter, an endoprosthesis, a coveringmember disposed about the endoprosthesis, a tip, and an end cap with adistally-tapered profile. The covering member can extend beyond an endof the endoprosthesis and on to the tip and/or end cap. The tip and/orend cap can comprise a region of reduced diameter. Further, the distalend of the covering member can terminate within the region of reduceddiameter.

With initial reference to FIG. 1, an endoprosthesis delivery system 100can comprise, in various instances, an elongate member 102 onto which anendoprosthesis 104 is mounted. Elongate member 102 and endoprosthesis104 can be surrounded by an outer shaft 150, such as an introducersheath, or other tubular shaft member. In various instances, elongatemember 102 and endoprosthesis 104 are passed through outer shaft 150 todeliver endoprosthesis 104 to a desired treatment area of a patient.

In various instances, endoprosthesis 104 comprises a compressiblemedical device. For example, in various embodiments, endoprosthesis 104comprises a stent or stent-graft. Conventional stent-grafts are designedto dilate from their delivery diameter, through a range of intermediarydiameters, up to a maximal, pre-determined functional diameter, andgenerally comprise one or more stent components with one or more graftmembers covering all or part of the inner and/or outer surfaces of thestent.

In various embodiments, endoprosthesis 104 comprises one or more stentcomponents made of nitinol and a graft member made of ePTFE. However,and as discussed below, any suitable combination of stent component(s)and graft member(s) is within the scope of the present disclosure.

For example, stent components can have various configurations such as,for example, rings, cut tubes, wound wires (or ribbons) or flatpatterned sheets rolled into a tubular form. Stent components can beformed from metallic, polymeric or natural materials and can compriseconventional medical grade materials such as nylon, polyacrylamide,polycarbonate, polyethylene, polyform aldehyde, polymethylmethacrylate,polypropylene, polytetrafluoroethylene, polytrifluorochlorethylene,polyvinylchloride, polyurethane, elastomeric organosilicon polymers;metals such as stainless steels, cobalt-chromium alloys and nitinol andbiologically derived materials such as bovine arteries/veins,pericardium and collagen. Stent components can also comprisebioresorbable materials such as poly(amino acids), poly(anhydrides),poly(caprolactones), poly(lactic/glycolic acid) polymers,poly(hydroxybutyrates) and poly(orthoesters). Any expandable stentcomponent configuration which can be delivered by a catheter is inaccordance with the present disclosure.

Potential materials for graft members include, for example, expandedpolytetrafluoroethylene (ePTFE), polyester, polyurethane,fluoropolymers, such as perfluoroelastomers and the like,polytetrafluoroethylene, silicones, urethanes, ultra high molecularweight polyethylene, aramid fibers, and combinations thereof. Otherembodiments for a graft member material can include high strengthpolymer fibers such as ultra high molecular weight polyethylene fibersor aramid fibers. Further, a graft may comprise a class of polyesterssuch as polyethylene terephthalate and polyaramids, polyfluorocarbonssuch as polytetrafluoroethylene (PTFE) with and without copolymerizedhexafluoropropylene, and porous or nonporous polyurethanes. Any graftmember that can be delivered by a catheter is in accordance with thepresent disclosure.

In various instances, system 100 further comprises a covering member 106surrounding at least a portion of endoprosthesis 104 and maintainingendoprosthesis 104 in a constrained configuration. For example, coveringmember 106 can comprise a plurality of woven warp knit or knit-braidfibers. In such embodiments, the distal and/or proximal end regions ofcovering member 106 can be longitudinally compressed against the end(s)of endoprosthesis 104.

System 100 can comprise, for example, a catheter tip 108. In variousembodiments, catheter tip 108 is positioned at a distal end of elongatemember 102 and distal to a distal end of endoprosthesis 104. Cathetertip 108 can comprise a distal end 118 having a tapered profile. Invarious embodiments, catheter tip 108 further comprises a proximal end120.

In various instances, system 100 further comprises an end cap 110. Endcap 110 may prevent covering member 106 from hanging-up on theendoprosthesis during deployment of endoprosthesis 104 (i.e., removal ofthe covering member from around endoprosthesis 104). End cap 110 cancomprise, for example, a mildly or moderately deformable material, i.e.,a low durometer polymeric material at least on the section closest tothe endoprosthesis. For example, the low durometer polymeric materialcan have a durometer between 15 and 70 Shore on the Type A scale. Invarious embodiments, the end cap 110 can be constructed so as to be morecompliant along the axis parallel to the longitudinal axis of theguiding member than across its radial dimension.

End cap 110 can comprise, for example, a cylindrical body 112. End cap110 can be located distal and adjacent to a distal end of endoprosthesis104. In various embodiments, endoprosthesis 104 can have a distal edgewhich can abut or be disposed adjacent to end cap 110. In variousembodiments, end cap 110 is integral to catheter tip 108. In otherembodiments, end cap 110 and catheter tip 108 are distinct elements andare not integral to each other. Further, end cap 110 and catheter tip108 can be spaced apart from one another, such that there is a gap orspace between proximal end 120 of catheter tip 108 and a distal end ofend cap 110. Although end cap 110 will be described with relation tocatheter tip 108 (i.e., proximal end 120 of catheter tip 108 will referto both the proximal end of catheter tip 108 and end cap 110), anyconfiguration of catheter tip 108 and end cap 110 is within the scope ofthe present disclosure.

End cap 110 can further comprise a region of reduced diameter 114. Invarious embodiments, region of reduced diameter 114 is located betweendistal end 118 and proximal end 120 of end cap 110. For example, regionof reduced diameter 114 can comprise a cylindrical portion of end cap110 that has a diameter less than that of cylindrical body 112.

In various instances, covering member 106 can extend beyond the distalend of endoprosthesis 104 and onto end cap 110. For example, the distalend of covering member 106 can be positioned along a region of reduceddiameter 114. The covering member 106 may encase a region of reduceddiameter 114 tightly and therefore have an effective constraineddiameter towards the distal end 118 of end cap 110 that is less than aneffective constrained diameter of the covering member 106 around a ridge122. In various embodiments, a portion of the distal end of coveringmember 106 can comprise a diameter less than that of cylindrical body112 and equal to or greater than that of region of reduced diameter 114.In such embodiments, the distal end of covering member 106 can besecured within region of reduced diameter 114 or perhaps along ridges122, which may assist in maintaining the position of the distal endduring delivery of endoprosthesis 104 and/or prevent premature orundesired retraction of the distal end of covering member 106.

With reference to FIGS. 1-3B, proximal end 120 of end cap 110 canfurther comprise a profile 116. In various embodiments, after deploymentof endoprosthesis 104, catheter tip 108 and end cap 110 are retractedback into outer shaft 150. Profile 116 may assist in retracting cathetertip 108 and end cap 110. For example, profile 116 can comprise a taperwhich may facilitate retraction of catheter tip 108 back into outershaft 150 by providing an angled face of proximal end 120 instead of aflat and/or square face of proximal end 120.

In certain instances, the end cap 110 may be described as including havevarious regions. For example, as shown in FIGS. 3A and 3B, the end cap110 may have an end cap proximal region 107 and an end cap distal region109. In some cases, as shown in FIGS. 3A and 3B, the end cap 110 mayinclude an end cap reduced diameter region 114 between the end capproximal region 107 and the end cap distal region 109. In addition, theend cap proximal region 107 may also include an end cap proximal regioneffective maximum diameter 105 and the end cap distal region 109 mayinclude an end cap distal region effective maximum diameter 103.

In certain instances, the end cap 110 may comprise various features. Forexample, as shown in FIG. 3C, the end cap 110 may comprise one or more(e.g., 2, 3, 4, 5, 6, or more) ridges 122. The ridges 122 may be in theend cap proximal region 107 as shown in FIG. 3C or they may exist inother regions, e.g., end cap distal region 109 or end cap reduceddiameter region 114. The ridges 122 may taper between the maximumdiameter 103 of the end cap 110 and the end cap reduced diameter region114. The ridges 122 may have a perpendicular portion 126 and a taperedportion 124 to a center line of an elongate member (e.g., 102) as shownin FIG. 3C. The tapered portion 124 may form an angle between 5 and 45degrees from a centerline (e.g., of endcap 110 or elongate member 102).For example, the tapered portion 124 may be approximately 5, 10, 15, 20,25, 30, 35, 40, or 45 degrees depending on application. The taperedportion 124 may have a larger effective diameter towards the distal end118 than the proximal end 120 of endcap 110 or alternatively the taperedportion 124 may have a larger effective diameter towards the proximalend 120 than the distal end 118. In addition, the ridges 122 may includerounded or flattened edges. The ridges 122 may have a flattened edgewith a range of approximately 0.02 mm to 0.2 mm or more. For example, aridge 122 may have a flattened edge of 0.02 mm, 0.06 mm, 0.12 mm, 0.14mm, 0.16 mm, 0.18 mm or 0.2 mm. A ridge 122 may also have a rounded edgewith a dimension ranging between approximately 0.02 mm and 0.4 mm. Forexample, a ridge 122 may have a rounded edge of approximately 0.02 mm,0.05 mm, 0.08 mm, 0.11 mm, 0.14 mm, 0.17 mm, 0.20 mm, 0.23 mm, 0.26 mm,0.29 mm, 0.32 mm, 0.35 mm, 0.038, 0.041 mm. The proximal end 120 of endcap 110 may abut the endoprosthesis 104. In certain instances, theendoprosthesis 104 may extend onto the proximal end 120 of endcap 110,and in other instances, the endoprosthesis 104 may extend up to theproximal end 120, as is shown in FIG. 3C. In certain instances, theridges may be used to help a covering member 106 to resist movement. Forexample, when the endoprosthesis delivery system 100 is inserted throughan introducer sheath or during manufacturing.

In certain instances, regions of the end cap can have various diameters.For example, as shown in FIGS. 3A-3C, the end cap proximal region 107and the end cap distal region 109 have effective maximum diameters (105,103) that are approximately equal. In FIGS. 4A-4C the end cap 110 hasvarying diameters. The ridges 122 may define the end cap proximal regionmaximum effective diameter 105. For example, as shown in FIG. 3C, theridges 122, define the end cap proximal region maximum effectivediameter 105. The end cap proximal region maximum effective diameter 105may be the same dimension as a constrained endoprosthesis 104 maximumeffective diameter.

As shown in FIGS. 3A-3C, the covering member 106 may extend along theendoprosthesis 104 and end cap proximal region 107. The covering member106 may lie essentially parallel to elongate member 102. The coveringmember may partially lie between ridges 122. In other cases, thecovering member 106 may taper from a larger diameter along theendoprosthesis 104 to a smaller diameter along end cap 110. The coveringmember 106 may be removed along end cap 110 and endoprosthesis 104,thereby exposing endoprosthesis 104 and thus allowing the endoprosthesisto be expanded. In some cases, the covering member 106 may more easilybe removed along end cap 110 and along a constrained endoprosthesis 104(e.g., an endoprosthesis with a scalloped distal end) if the maximumeffective diameters of the end cap 110 and endoprosthesis 104 areapproximately equal. The endoprosthesis 104 may have a graft portion anda stent portion. The endoprosthesis 104 may also include stent portionsthat extend beyond the graft portion. These stent portions may includevarious shapes, such as scalloped ends. In other cases, it may bebeneficial to have constrained endoprosthesis 104 have an effectivemaximum diameter that is greater than the effective maximum diameter ofthe end cap 110.

Profile 116 can comprise, for example a continuous taper. In otherembodiments, with initial reference to FIG. 4A, profile 116 can comprisea “staged” taper. For example, profile 116 can comprise one or moretapered segments 440 and 442. Tapered segments 440 and 442 can beseparated by one or more non-tapered segments. Profiles 116 comprisingany configuration and number of tapered segments are within the scope ofthe present disclosure.

In various embodiments, end cap 110 can further comprise one more fins230. In such embodiments, fins 230 are positioned at the proximal end120. For example, one or more fins 230 can be located along profile 116of proximal end 120. In various embodiments, fins 230 can comprise aprotrusion from profile 116. For example, as end cap 110 and cathetertip 108 are retracted into outer shaft 150, the proximal end of outershaft 150 can exert pressure on fins 230, causing them to fold over. Byat least partially folding over, fins 230 may reduce the difficulty inretracting catheter tip 108 and end cap 110 back into outer shaft 150.

In various embodiments, fins 230 may provide a resistance to radialforces against an outer surface of end cap 110. For example, fins 230may be subjected to a radial compressive force by endoprosthesis 104and/or covering member 106. Fins 230 may resist such compressive forcesand maintain a relatively constant diameter. In various embodiments,characteristics of fins 230 such as thickness, material, and length,among others, may be selected to provide sufficient resistance to radialforces while maintaining the ability of the fins to fold over whenretracted into outer shaft 150.

With initial reference to FIGS. 4B and 4C, fins 230 can be positioned onend cap 110 in various configurations. For example, as illustrated inFIG. 4B, fins 230 can traverse the length of the taper of profile 116.In other embodiments, as illustrated in FIG. 4C, fins 230 can bepositioned along a portion of the length of the taper of profile 116(instead of the entire length of the taper). Further, fins 230 can bepositioned in any combination of arrangements, including one or morefins 230 located along one or more different portions of the length ofthe taper of profile 116. Any positioning of fins 230 along profile 116,including combinations of different positions, is within the scope ofthe present disclosure.

In various embodiments, fins 230 can have the same or nearly the samediameter as cylindrical body 112. Such fins 230 can provide a constantdiameter, and therefore a consistent surface of support, for coveringmember 106. For example, as illustrated in FIG. 4C, fins 230 maycomprise a diameter less than the diameter of cylindrical body 112.Although described as having the same diameter as cylindrical body 112,fins 230 can comprise any suitable diameter, including multiple portionsor regions having different diameters.

With initial reference to FIG. 5, multiple fins 230 located at proximalend 120 of end cap 110 are illustrated. For example, to assist inunderstanding the spatial relationship and orientation of fins 230 andend cap 110, end cap 110 can comprise a longitudinal axis 532. Invarious embodiments, fins 230 are oriented such that a plane 534parallel to fin 230 is parallel to and intersects with a portion of thelength of longitudinal axis 532. Stated another way, in suchembodiments, fins 230 are generally “straight” relative to longitudinalaxis 532.

With initial reference to FIG. 6, multiple fins 230 located at proximalend 120 of end cap 110 are illustrated. In various embodiments, fins 230are oriented such that a plane 534 parallel to fin 230 is non-parallelto and intersecting at a point with longitudinal axis 532. Statedanother way, in such embodiments, fins 230 are generally “angled”relative to longitudinal axis 532.

Although described in connection with two specific examples (e.g., the“straight” fins of FIG. 5 and the “angled” fins of FIG. 6), fins 230 canbe configured in any way that provides support to covering member 106 atproximal end 120 of end cap 110. For example, fins 230 can be curved,bent, or otherwise non-straight. Any suitable configuration of fin 230is in accordance with the present disclosure.

Numerous characteristics and advantages have been set forth in thepreceding description, including various alternatives together withdetails of the structure and function of the devices and/or methods. Thedisclosure is intended as illustrative only and as such is not intendedto be exhaustive. It will be evident to those skilled in the art thatvarious modifications may be made, especially in matters of structure,materials, elements, components, shape, size, and arrangement of partsincluding combinations within the principles of the invention, to thefull extent indicated by the broad, general meaning of the terms inwhich the appended claims are expressed. To the extent that thesevarious modifications do not depart from the spirit and scope of theappended claims, they are intended to be encompassed therein.

Further, any combination of the elements and components of the presentdisclosure is within the scope of the present invention. Moreover, wherea phrase similar to “at least one of A, B, or C” is used in the claims,it is intended that the phrase be interpreted to mean that A alone maybe present in an embodiment, B alone may be present in an embodiment, Calone may be present in an embodiment, or that any combination of theelements A, B and C may be present in a single embodiment; for example,A and B, A and C, B and C, or A and B and C.

What is claimed is:
 1. An endoprosthesis delivery system comprising: anelongate member having a proximal end and a distal end, the elongatemember being configured to support an endoprosthesis proximal to itsdistal end; and an end cap having a proximal end and a distal end, theproximal end of the end cap including a section having a reducedprofile, wherein the reduced profile includes a protrusion that isconfigured to support a covering member surrounding the endoprosthesis;wherein the end cap is coupled to the elongate member such that theproximal end of the end cap is adjacent and distal to the distal end ofthe elongate member.
 2. The endoprosthesis delivery system of claim 1,wherein the reduced profile includes a taper that decreases in diameterproximally.
 3. The endoprosthesis delivery system of claim 1, whereinthe protrusion is a fin.
 4. The endoprosthesis delivery system of claim3, wherein the fin has a length, a width, and a height.
 5. Theendoprosthesis delivery system of claim 4, wherein the length of the fincorresponds to a length of the section having the reduced profile. 6.The endoprosthesis delivery system of claim 4, wherein a length of thesection having the reduced profile exceeds the length of the fin.
 7. Theendoprosthesis delivery system of claim 4, wherein the height of the fincorresponds to a diameter of the end cap in a region distal to thesection having the reduced profile.
 8. The endoprosthesis deliverysystem of claim 4, wherein the fin is curved, bent, or otherwisenon-straight along its length.
 9. The endoprosthesis delivery system ofclaim 3, wherein the fin is straight relative to a longitudinal axis ofthe end cap.
 10. The endoprosthesis delivery system of claim 9, whereinthe fin extends along the section having the reduced profile such thatthat a plane parallel to the fin is parallel to and intersects with thelongitudinal axis of the end cap.
 11. The endoprosthesis delivery systemof claim 3, wherein the fin is angled relative to a longitudinal axis ofthe end cap.
 12. The endoprosthesis delivery system of claim 11, whereinthe fin extends along the section having the reduced profile such thatthat a plane parallel to the fin is non-parallel with and intersectswith the longitudinal axis of the end cap.
 13. The endoprosthesisdelivery system of claim 3, wherein the end cap includes a plurality offins.
 14. The endoprosthesis delivery system of claim 3, furthercomprising an outer shaft, and wherein the fin is configured to deflectupon retraction of the end cap into the outer shaft.
 15. Theendoprosthesis delivery system of claim 14, wherein the fin isconfigured to fold upon retraction of the end cap into the outer shaft.16. The endoprosthesis delivery system of claim 1, wherein the sectionhaving the reduced profile includes a plurality of ridges that definethe protrusion.
 17. An endoprosthesis delivery system comprising: anelongate member; an endoprosthesis disposed about the elongate member;and an end cap positioned such that a proximal end of the end cap isdistal to a distal end of the endoprosthesis; wherein the proximal endof the end cap comprises a section having a reduced profile, and whereinthe reduced profile includes a protrusion that is configured to deflectto allow for retraction of the end cap into an outer shaft.
 18. Theendoprosthesis delivery system of claim 17, wherein the reduced profileincludes a taper that decreases in diameter proximally.
 19. Theendoprosthesis delivery system of claim 17, wherein the protrusion is afin.
 20. The endoprosthesis delivery system of claim 19, wherein the finhas a length, a width, and a height.
 21. The endoprosthesis deliverysystem of claim 20, wherein the length of the fin corresponds to alength of the section having the reduced profile.
 22. The endoprosthesisdelivery system of claim 20, wherein a length of the section having thereduced profile exceeds the length of the fin.
 23. The endoprosthesisdelivery system of claim 20, wherein the height of the fin correspondsto a diameter of the endoprosthesis when constrained in a deliveryconfiguration.
 24. The endoprosthesis delivery system of claim 20,wherein the fin is curved, bent, or otherwise non-straight along itslength.
 25. The endoprosthesis delivery system of claim 19, wherein thefin is straight relative to a longitudinal axis of the end cap.
 26. Theendoprosthesis delivery system of claim 25, wherein the fin extendsalong the section having the reduced profile such that that a planeparallel to the fin is parallel to and intersects with the longitudinalaxis of the end cap.
 27. The endoprosthesis delivery system of claim 19,wherein the fin is angled relative to a longitudinal axis of the endcap.
 28. The endoprosthesis delivery system of claim 27, wherein the finextends along the section having the reduced profile such that that aplane parallel to the fin is non-parallel with and intersects with thelongitudinal axis of the end cap.
 29. The endoprosthesis delivery systemof claim 19, wherein the end cap includes a plurality of fins.
 30. Theendoprosthesis delivery system of claim 19, wherein the fin isconfigured to fold upon retraction of the end cap into the outer shaft.31. The endoprosthesis delivery system of claim 17, wherein the sectionhaving the reduced profile includes a plurality of ridges that definethe protrusion.
 32. The endoprosthesis delivery system of claim 17,wherein the endoprosthesis is a stent.
 33. The endoprosthesis deliverysystem of claim 17, wherein the endoprosthesis is a stent-graft.